California Water District Launches Program To Combat Invasive Mollusk

Feb 01, 2007

On Feb. 13, the board of directors of the Metropolitan Water District of Southern California (MWDSC) launched a program to detect and control an invasion of quagga mussels in the regional water import and drinking water treatment system.

Quagga mussels, which are related to the notorious zebra mussels that have overrun the Great Lakes and Mississippi River watershed, were found on Jan. 6 in Lake Mead, and were subsequently found at MWDSC 's Whitsett Intake Pumping Plant on Lake Havasu and the nearby Gene Wash Reservoir.

The mussels, which are spread by commercial ships and recreational boats, can multiply rapidly, clog pipes and pumping machinery, and ruin the ecology of lakes and reservoirs. Once the ecology is altered, the growth of algae can occur and affect the taste of a region's drinking water.

"With recent evidence that quagga mussels have infested the entry portals of our Colorado River Aqueduct system, this is the initial stage of a three-phase program to detect, assess and control these invaders," said MWDSC General Manager Jeff Kightlinger. "This control program will not only protect critical water supply infrastructure in Southern California, but will safeguard the extensive freshwater fisheries in our Diamond Valley Lake and Lake Skinner reservoirs."

The first phase of the program was approved unanimously by MWDSC's board and will be launched immediately with the purchase of $180,000 of portable decontamination units, deep-water surveillance equipment, automated water samplers and a $16,000 polarizing microscope. It also includes increased surveillance of MWDSC's aqueduct and reservoirs by divers and maintenance personnel, and laboratory inspections of water samples.

Dr. Ric De Leon, MWDSC's microbiology manager, said the program's first phase should be completed in six months, at which time results and recommendations will be reported to MWDSC's board.

The results of the surveillance, studies and vulnerability assessment conducted during the first phase will be used to prioritize infrastructure upgrades and develop control measures for subsequent phases of the program. The results also will help in the development of recommendations for changes in boating practices or additional facilities needed to control the spread of the mussels at Diamond Valley Lake and Lake Skinner.

During MWDSC's initial quagga discovery -- the first verified finding of the mussel in California -- divers found low densities of the mussels, ranging in size from a quarter-inch to 1 1/4-inches wide, attached to concrete surfaces and anchors at depths of 30 feet to 40 feet during an inspection at the Whitsett Intake plant. Additional small numbers of quagga were found later at Gene Wash, which serves as a forebay for another nearby pumping plant along MWDSC's aqueduct.

Although subsequent underwater inspections of MWDSC reservoirs, including Diamond Valley Lake and Lake Skinner, have failed to turn up any additional mussels, the district would take aggressive action to control the number of quagga in its aqueduct system and protect the district's raw (untreated) water conveyance system from further invasion, said Debra C. Man, MWDSC's chief operating officer.

"Controlling the spread of this mussel in our water system is a top priority for us," Man said. "We plan to take every action necessary to protect and maintain the reliability of our aqueduct, lakes, pipelines and other facilities."

The Metropolitan Water District of Southern California (http://www.mwdh2o.com) is a cooperative of 26 cities and water agencies serving 18 million people in six counties. The district imports water from the Colorado River and Northern California to supplement local supplies, and helps its members to develop increased water conservation, recycling, storage and other resource-management programs.